# Electrical Machine Interview Questions With Answer | 100 DC And AC Machine Questions Collection

An electrical device which convert Electrical Engineering to Mechanical Engineering or Mechanical Engineering is known as Electrical Machine. In this post, I am going to share top 100 DC and AC Electrical Machine Interview Questions With Answer for the entrance exam. These questions are collected from different sources and will cover generator, Motor and Transformer.

## Electrical Machine Interview Questions With Answer

Here you will get basic electrical machines objective questions and answers for all interview exam.

Q1. Explain the working principle of an electric machine?

Ans: Woking of DC Machine is based on Faraday’s Laws of Electromagnetic Induction. According to this law when we place a current carrying conductor in a magnetic field, Then electromagnetic force is induced which tends to move conductor. Its based on Flamming left-hand rules. the magnitude of this emf is given by F = BIL.

Q.2 Describe Classifications of DC machines?

Ans: Both DC motor and DC generators work on the same principle so both are classified in two categorised.

• Separately Excited Machine: In this type of DC Machines, field winding is supplied from a separate power source.
• Self Excited Machine: In this types of Machine, field winding and armature winding are interconnected. Next Self Excited Machines also classified in three parts. 1. Series wound, 2. Shunt wound and 3. Compound wound.

I have seen a lot of candidates are looking for electrical interview questions and answers on electrical machines pdf download, but they can not download. Here I have collected all these questions from different exam and books. All these are basics of electrical machines interview questions and will be very helpful to you. Keep Reading.

Q.3 Explain Basic construction of DC Machine?

Ans: Here is basic construction of DC Machine.

1. Yoke: This is outer part of any Machine.
2. Poles and pole shoes.
3. Field winding.
4. Armature core and Armature winding.
5. Commutator and brushes

Q.4 What is Rotor And Stator?

Ans: In any Electrical Machine, rotating part is known as rotor and stationary part is called as stator.

## Electrical Machines Questions and Answers Pdf

Q.5 What is Electrical Transformer?

Ans: Electrical transformer is a static device which transforms electrical energy from one circuit to another without any direct electrical connection. You can read this article for Electrical Transformer Interview Questions. Check GTU Time Table 2018 here.

Q.6 Explain the principle of the transformer?

Ans: Transformer works on the Faraday Law’s Of Electromagnetic induction and principle of mutual induction of two coils. According to this, When the current in the primary coil is changed the flux linked to the secondary coil also changes. By this, an EMF is induced in the secondary coil.

Q.7 What is the PMSM?
Ans: In medium and small size synchronous motors, DC field can be produced by permanent magnets. Such kind of motors are called as PMSM

Q.8 How many types of Electrical Machine?
ANS. Mainly there are two types of electric Machine:

• AC Machine
• DC Machine

Q.9 Write an expression for synchronous speed?
Ans: An expression for synchronous speed is NS = 120f/P.
Where
f = frequency
P = No of poles of the machine.

Q.10 Define torque (May-2010)
Ans: A turning or a twisting force about an axis is called as torque.

## Electrical Machines Objective Questions With Solutions

In this section I am sharing mcq on electrical machines pdf. If you are Electrical Engineer and looking for same, here you can download dc machines multiple choice questions and answers in format pdf.

Q.1 The percentage of silicon in transformer stampings is usually limited to?

1. 0.4%
2. 1.4%
3. 4%
4. 14%.
Q.2 The density of hydrogen is _____ times the density of air?
1. 0.07{Right}
2. 1.5
3. 2.5
4. 3.5

Q.3 Power transformers have the rating?

1. Equal to 50 kVA
2. Equal to 100 kVA
3. Above 200 kVA
4. None of the above

Q.4 In 8 – pole wave connected motor armature, the number of parallel paths are?

1. 8
2. 4
3. 2
4. 1

Q.5 The power factor of a squirrel cage induction motor is

1. Low at light load only.
2. Low at heavy load only.
3. Low at the light and heavy load both.
4. Low at rated load only.

## Electrical Machine Unsolved Interview Questions

1. What is the difference between Electrical and Electronics Engineering?
2. What is the difference between battery and a capacitor?
3. What is the difference between real ground and virtual ground?
4. What is the fundamental difference between EMF(Electro Motive force) and PD(Potential Difference)?
5. What is the motor starter and why we need a starter to install a motor?
6. What is the Q factor in Electrical and Electronics Engineering?
7. Difference between Uni-lateral and Bi-lateral circuits and elements?
8. What is the main difference between linear and non-linear circuits?
9. What is the difference between AC and DC resistance?
10. What is the difference between Active and passive components?
11. Explain about single phase induction motor?
12. What isbasicallythe difference between Step-up and Step-down transformers?
13. What is Alternator and how it works?
14. What is voltage regulator?
15. Explain about voltage divider,voltage doubler,voltage multiplier…etc ?
I have collected these questions from various competitive exams and interviews. Mostly, All organizations ask these question when it comes to Electrical Machine Interview Questions. If you are preparing for GATE/IES/UPSE/SSC/PSUs and State level Exams, you should read these MCQs question for the better result.
Electrical Machine Interview Questions With Answer | 100 DC And AC Machine Questions Collection
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